Determining Bathymetry of Shallow and Ephemeral Desert Lakes Using Satellite Imagery and Altimetry

©2020. American Geophysical Union. All Rights Reserved. Water volume estimates of shallow desert lakes are the basis for water balance calculations, important both for water resource management and paleohydrology/climatology. Water volumes are typically inferred from bathymetry mapping; however, being shallow, ephemeral, and remote, bathymetric surveys are scarce in such lakes. We propose a new, remote-sensing-based, method to derive the bathymetry of such lakes using the relation between water occurrence, during \u3e30 year of optical satellite data, and accurate elevation measurements from the new Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2). We demonstrate our method at three locations where we map bathymetries with ~0.3 m error. This method complements other remotely sensed, bathymetry-mapping methods as it can be applied to: (a) complex lake systems with subbasins, (b) remote lakes with no in-situ records, and (c) flooded lakes. The proposed method can be easily implemented in other shallow lakes as it builds on publically accessible global data sets

A flexible and wearable energy harvester with an efficient and fast-converging analog MPPT

peer reviewedThis paper presents a flexible energy harvesting system with an analog maximum power point tracking (MPPT) algorithm that operates using the output current. The proposed MPPT circuit is simplified as only one parameter needs to be measured and is implemented by fully analog design. Simulation and experiment results validate that the proposed MPPT algorithm has a tracking efficiency of 93.7% with a fast converging speed. The energy harvesting system is implemented and tested with a flexible solar panel, and thus can be used in wearable devices. © 2016 IEEE

The Impact of Extreme Rainstorms on Escarpment Morphology in Arid Areas: Insights From the Central Negev Desert

The impact of climate on topography, which is a theme in landscape evolution studies, has been demonstrated, mostly, at mountain range scales and across climate zones. However, in drylands, spatiotemporal discontinuities of rainfall and the crucial role of extreme rainstorms raise questions and challenges in identifying climate properties that govern surface processes. Here, we combine methods to examine hyperarid escarpment sensitivity to storm-scale forcing. Using a high-resolution DEM and field measurements, we analyzed the topography of a 40-km-long escarpment in the Negev desert (Israel). We also used rainfall intensity data from a convection-permitting numerical weather model for storm-scale statistical analysis. We conducted hydrological simulations of synthetic rainstorms, revealing the frequency of sediment mobilization along the sub-cliff slopes. Results show that cliff gradients along the hyperarid escarpment increase systematically from the wetter (90 mm yr(-1)) southwestern to the drier (45 mm yr(-1)) northeastern sides. Also, sub-cliff slopes at the southwestern study site are longer and associated with milder gradients and coarser sediments. Storm-scale statistical analysis reveals a trend of increasing extreme (>10 years return-period) intensities toward the northeast site, opposite to the trend in mean annual rainfall. Hydrological simulations based on these statistics indicate a higher frequency of sediment mobilization in the northeast, which can explain the pronounced topographic differences between the sites. The variations in landscape and rainstorm properties across a relatively short distance highlight the sensitivity of arid landforms to extreme events